Electrochemical energy as a source of reducing equivalent was applied to the cultures of Clostridumacetobutylicum to understand the effects of the pressure by reducing equivalent on anaerobic bacteria. The fermentation by C.acetobutylicum with methyl viologen and electrochemical energy produced more butanol (up to 26%) than the control culture, whilst less acetone (up to 25%) was produced. But no effect was observed on the growth of the culture. These results were indirectly supported by invitro electrochemical reduction of NAD+ and artificial electron carriers.